The final lecture in the 2012 Frank Davis Lecture Series was given by Prof Toshio Watanabe, from the University of the Arts, London. At its centre was an extraordinary object, the Ryoanji Garden in Kyoto, regarded as one of the finest examples of the Japanese Zen garden. As we discovered in Prof Watanabe’s fascinating lecture, Ryoanji’s canonical status is a more complicated affair than the garden’s antiquity might suggest.

I have, I confess, very little knowledge of Japanese dry gardens, and the lecture slides filled me with a mixture of wonder tinged with bafflement. In the everyday meaning of the term, Ryoanji is scarcely a garden at all: it’s a rectangle of raked shingles, in which a small number of rocks have been significantly placed; the only vegetation is small patches of moss forming islands around these mysterious objects. The garden’s history, in Watanabe’s account, only adds to its strangeness: its designer is unknown, and it was constructed at some point between the fifteenth and seventeenth centuries (recent scholarship favours the later date). Its austere beauty, as part of the Ryoanji temple complex, clearly suggests a contemplative purpose, though the ritual or symbolic intent of its authors remains a matter of scholarly conjecture.

The subject of the lecture was not the history of Japanese gardens – though I would have been happy enough to sit through that. Watanabe’s theme was the creation of canons, a process that results, in Ryoanji’s case, in 300,000 visitors a year. It turns out that the origins of this pilgrimage are not lost in the mists of time, but can be specifically dated to the inclusion of Ryoanji in guides to Japanese gardens from the 1920s onwards. The key turning point was 1935, when the American author Lorraine Kuck linked the garden to Zen Buddhism in her book One Hundred Kyoto Gardens – previous scholars had been more circumspect in their claims, if they mentioned Ryoanji at all. The lecture then sketched out the progress toward Ryoanji’s present-day mythic status, passing through American transcendentalism (five million copies of Zen and the Art of Motorcycle Maintenance), the Tokyo Olympics of 1964, and the works of John Cage. At some point along the way, Kuck’s speculative theory of Ryoanji’s Zen credentials became hardened into certainty.

The joy of Prof Watanabe’s lecture was that it spoke, with great clarity, to a fundamental issue in the history of art. How do works of art enter the canon, and what does this inclusion signify? A simple appeal to artistic quality is, clearly, inadequate: works may be elevated or ignored for all kinds of contingent reasons. Watanabe did not suggest that we can do without the canon – it’s basic to cultural value systems, and to the creation of interest groups – only that we should be aware of the complex power relations that underlie them. And that, as the Ryoanji example perfectly illustrated, historians need on occasion to follow received wisdom back to its original sources.